My cousins in Southern Saskatchewan tried raising catallo, hoping the buffalo bull they bought would breed with their Herefords (white faces).
As the seasons changed, they'd get calls from the neighbours "come and get your damn buffalo off my property". With seasons changing, they would just walk through a fence. Seems to me they had one bull and about 6 or 7 cows total.
They all ended up in various "freezers". The 16 sections of ranch land was not big enough to contain the buffalo. The fences were just not up to the task - 3 wire fences only.
Just South of here there is a "ranch" with buffalo and the fences are all at least 8 strands, 7' high, wires close together and have 6' boards standing vertically in the wires every couple feet, along with vertical wires as well. They are substantial fences and seem to work.